A Sound Plan: How Distinct Weapon Sounds, Attention to Detail, and Crafting Accurate Reverb and Echoes Adds Layers of Audio Amazement to Call of Duty: Modern Warfare.

By now you should have read up on the meticulously-crafted Single Player Campaign narrative, the lengths the art team went to in order to obtain the most incredible graphics ever seen in a Call of Duty® game, checked out the wealth of technical advancements the new game engine allows the developers at Infinity Ward to utilize, and inspected the ways in which weapon animation reaches new levels of fidelity. However, just as important as any ray-traced reflection or weapon magazine reload are the enticing and exceptional sounds you’ll hear in the game.

Gas Piston, Direct Impingement, Bolt Action: Distinct Weapon Voices.

Stephen Miller, Audio Director at Infinity Ward, heads up the team responsible for everything you’ll hear in the game, and the following interview gives you an overview of how he and the audio team researched and improved the sounds of the weapons you’ll be using. This is important, Stephen says, as “each weapon must have its own unique voice.” Part of the distinctly-different sound every armament possesses is down to its operating system: “Whether it’s a gas piston, direct impingement, or bolt action, all of this brings a different type of voice to a weapon.”

Imagine, if you will, the quick and rapid staccato sound; the familiar burst from an assault rifle. As well as the weapon’s sound, there are other effects the audio team considered, too: “You’re hearing the weapon fire, but you’re also hearing the shell eject from the weapon.” For Modern Warfare, the sound of each individual shell, travelling in 3D space, as it moves through the air, is also audible, “before it actually impacts on the ground, using a physics system for all of this.” The weapons also have a weighty feel to them. Nestle a weapon stock to your chest, and there’s a familiar kick back: “We made sure you felt something akin to a nice thump to the chest.”

90 Microphones in the Desert

Miller’s team went out on a number of field trip recording sessions to ensure audio accuracy too: “We recorded all of our weapons, out in the desert and all kinds of other locations. We used about 90 different microphones to capture each shot.” Groups of microphones provided different audio functionality, too: “That’s for all kinds of perspectives. Twenty of those are for the player perspective alone. Using all of that detail, we were able to capture different perspectives; those from when you’re at the hip, and those when you’re aiming down sight….”

Weapon sounds also interact with the environment. “This is super important to us, Stephen says; “we couldn’t make the game without the sounds being relevant to the place, whether that’s Piccadilly Circus, the desert, the mountains or wherever.” The team employed a number of new systems to add environmental effects to weapon audio: “The first is reverb and slap delay DSP [digital signal processing] system. The second is an atmospheric layer that is contextual and plays along with every weapon shot. The third is a weapon reflection system.” With the audio existing in 3D space, expect variations in sound depending on how and where you’re listening to each weapon fire.

Reverb, Atmosphere, and Reflection: All at the Speed of Sound

Weapon reflection system? Think about the nuances of noise and atmosphere and how it plays with your ears: “Every time you shoot a gun, the sound travels out into the world, and the game knows where the sound will interact with the environments and plays a specific sound at those locations.” All of this is contextual. Whether you’re up next to a building, down in front of a car, or inside a subway tunnel, the reflected sound of each weapon has an appropriate audio effect.

Infinity Ward took this one step further, as Stephen explains: “having sound behave realistically is super-important to us, so as those sounds go out into the environment and bounce back to us, they do so with authenticity and clarity, at the speed of sound, and as close to how you’d hear it occur in reality. There is natural delay and decay to every weapon noise.” The results are exceptional immersive soundscapes: “The sound gives you a big, deep, booming echo in larger expanses of scenery, while the same weapon becomes slightly more muffled, far less reverberating, and with less echo in more confined environments.”

Stephen and the audio engineers also took these aspects and ran with them: “We didn’t want to stop there, so we decided to do the same for all our explosions. These are just some of the pieces of the puzzle that we’ve all been trying to put together reimagining what Modern Warfare is to us, grounding you into our whole new world. And giving you a whole lot of fun.”

Stephen is justly proud of his team’s work: “It must be heard to be believed.”